Continuity mistake: At the school, when Scott's suit is malfunctioning and he's big in the janitor's closet, his head is tilted towards his right shoulder. When Hope is working on the suit, we see Scott's head is now tilted towards his left shoulder, even though he's stuck and wouldn't have been able to move around like that. But in the next shot it's back to his right.
Continuity mistake: The outside of Hank's lab changes in different shots - sometimes there's a "no entry" sign inside a window on the right, other times it's missing. When Scott and Hope arrive there's a red logo on the door which is missing later. And when the ghost exits there's a "private property" notice beside the door which isn't there at other times.
Continuity mistake: As the ghost attacks Wasp in the hotel lobby, there's a guy unconscious in front of the piano who's there in some shots and missing in others.
Continuity mistake: While Hope is talking with Burch at the restaurant the bag of money and the device are on the table but in the next shot the device is now on the seat.
Continuity mistake: When Susan goes to visit Burch and enters the building, she has the suitcase in her right hand but in the next shot she has it in her left hand. (00:21:45)
Continuity mistake: When the shrunken car is surrounded by pigeons, it's an all-glass roof, or black. When the shrunken car drives through a pipe later, its roof is silver. It changes back and forth again, just before/after Hank shrinks it.
Continuity mistake: At the start when Hope is playing in her room, in a wide shot there's a wooden stand with a plant on it by the teddy bear in the background. In a closeup of her this stand has vanished.